A Dynamic Mesh Display Representation for the Holodeck Ray Cache System

This report presents a dynamic mesh representation that is designed to display the results of interactively sampling a 3D environment. The mesh generator takes samples comprising a world space location, RGB color value, and sampled ray direction, and assembles them into a 3D triangle mesh. From this representation a complete image can be constructed and displayed, both from the initial view, and from subsequent views as the user moves through the environment. The representation exploits the fact that from a xed vantage point there is a one-to-one mapping between visible world space points and their projection onto a sphere centered at that viewpoint. A Delaunay triangulation constructed on the sphere provides the mesh topology and the the vertex coordinates are derived from the input samples. The resulting mesh is used as the 2.5D display representation. The mesh is dynamic and ephemeral: it is updated as samples are added and deleted, and reconstructed after signiicant viewpoint changes. The dynamic mesh representation is described in the context of an interactive rendering system based on the holodeck, a 4-dimensional ray-caching data structure. In the holodeck system, a display driver makes requests for ray samples based on the user's current view. The display driver must then quickly construct a coherent image based on these samples. This report introduces the dynamic mesh representation as a solution to the reconstruction problem, describes its implementation, and presents the results of utilizing this representation in the holodeck environment.